Electric wheeled apparatus

ABSTRACT

An electric wheeled apparatus comprises a main body, at least one wheel supported by the main body in a rotatable manner; an electric motor configured to apply torque to the at least one wheel, a battery interface configured to removably receive at least one battery pack which is originally designed as a power source of an electric power tool, and an electric circuit unit configured to electrically connect the at least one battery pack attached to the battery interface with the electric motor.

CROSS-REFERENCE TO A RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2009-209175 filed on Sept. 10, 2010 and Japanese Patent Application No.2009-265917 filed on Nov. 24, 2010, the contents of which are herebyincorporated by reference into the present application.

TECHNICAL FIELD

The present invention relates to an electric wheeled apparatus. Inparticular, the present invention relates to an electric wheeledapparatus that uses a rechargeable battery pack as a power source, andwhich has an electric motor that drives a wheel. Here, the electricwheeled apparatus includes vehicles ridden by people, such as electricbicycles (electric assist bicycles, hybrid bicycles), electricmotorcycles, electric wheelchairs, electric automobiles, hybridautomobiles (not limited to those having an engine), various electricwork vehicles (e.g., forklifts, sanitation vehicles), and electric toysthat can be ridden, as well vehicles not ridden by people, such aselectric carrier carts, electric lifters, electric unmanned carriers,and electric wirelessly operated toys. Furthermore, an electric wheeledapparatus also includes vehicles having endless treads that are drivenby wheels (also known as a crawler track or Caterpillar (registeredtrademark)).

DESCRIPTION OF RELATED ART

An electric bicycle (one type of electric wheeled apparatus) isdisclosed in Japanese Application Publication No. 2008-62814. Thiselectric bicycle comprises two wheels that are rotatably provided on avehicle body, pedals to which the user applies force, a user forcetransmission that transmits the force that was applied to the pedals tothe wheels, an electric motor that applies torque to the wheels, and abattery pack that supplies electric power to the electric motor. Withthis type of electric bicycle, the electric power supplied from thebattery pack to the electric motor will be adjusted in response to theforce applied to the pedals by the user and the speed of the electricbicycle. The user can receive auxiliary force from the electric motor,and easily pump the pedals.

SUMMARY OF THE INVENTION

As with the aforementioned electric bicycle, a large number of electricwheeled apparatuses have been developed that use a rechargeable batterypack. With these types of electric wheeled apparatuses, a dedicatedbattery pack is used for each product, and the battery packs of otherproducts cannot be used. Furthermore, with conventional electric wheeledapparatuses, countermeasures are taken to prohibit the use of batterypacks from other products. Because of that, even if a user of anelectric wheeled apparatus owns a large number of battery packs for avariety of other products, the user must use a dedicated charger inorder to recharge that battery pack. As a result, the user must own manytypes of battery packs and chargers, and must manage the usage state andcharge state of many different types of battery packs.

In regard to the aforementioned problems, the present inventors havefocused on battery packs used for electric power tools. The reasons forthat are as follows.

First, compared to battery packs for other portable devices, the batterypacks used in electric power tools have a high output voltage and alarge recharging capacity, and is sufficient for use as the power sourcein an electric wheeled apparatus. In addition, because there are manybattery packs for electric power tools that are used in harsh conditions(such as outdoors, etc.), many superior technologies have been developedand employed therein, and the reliability of these products is excellent(i.e., they rarely break down).

Second, there are many users of electric power tools that own aplurality of battery packs for one electric power tool, so that theelectric power tool can be used for a long period of time. However,because there is only a small chance that the electric power tool infact is used for a long period of time, a frequency with which eachbattery pack is used is low, and as a practical matter, the batterypacks that one owns are not made good use thereof. In this case, thebattery packs for use in the electric power tools that the user owns canbe effectively used if they can also be used in the electric wheeledapparatus. For example, the user who uses an electric power tool at workcan use the battery pack for the electric power tool in the electricwheeled apparatus during leisure time.

Third, there are many electric power tools that are used in a variety ofmanufacturing plants and construction sites. The workers in themanufacturing plants and construction sites will sometime carry theelectric power tools, as well as travel around work sites by theelectric wheeled apparatuses. In this case, there hardly is any casethat the workers use the electric wheeled apparatuses and the electricpower tools at the same time. In other words, the electric power tool israrely used while travelling on the electric wheeled apparatus, and theelectric wheeled apparatus is rarely used while working with theelectric power tool. Thus, if the electric wheeled apparatus can use thebattery pack for the electric power tool, the battery pack can be usedin the electric wheeled apparatus while the electric wheeled apparatusis being used, and the battery pack can be used in the electric powertool when work is being performed with the electric power tool. Thebattery pack can be effectively used, and also a number of battery packsthat must be transported to the work site can be reduced. Alternatively,it is also possible that only the electric power tool is transported tothe work site by an electric unmanned carrier, without any workertraveling on the electric unmanned carrier. Even in this case, by usingthe battery pack on the unmanned carrier when transporting the electricpower tool, and using the same battery pack in the electric power toolat the work site, the battery pack for the electric power tool can beeffectively used.

Based upon the aforementioned present teachings, a new and usefulelectric wheeled apparatus can be realized. This electric wheeledapparatus comprises a main body, a wheel that is rotatably provided onthe main body, an electric motor that applies torque to the wheel, abattery interface that can removably receive a battery pack for anelectric power tool, and an electric circuit unit that electricallyconnects the battery pack attached to the battery interface to theelectric motor.

The electric wheeled apparatus can use the battery pack of the electricpower tool as a power source, and a dedicated battery pack and chargerare not necessary. The user of the electric power tool can also makegood use of the battery pack for the electric power tool that the userowns in the electric wheeled apparatus. Because the battery pack is usedfrequently, it will not be wasteful to own multiple battery packs, andby owning multiple battery packs, it will become possible to use theelectric power tool for a long period of time when needed.

The electric wheeled apparatus according to the present teachingsincludes all types of electric power tools, for example, electric drillsthat drive a drill bit with electric power, electric screwdrivers thatdrive a screwdriver bit with electric power, electric wrenches thatdrive a wrench bit with electric power, electric grinders that drive awhetstone with electric power, electric hammers that drive chisels withelectric power, electric saws that drive a saw blade with electric power(including circular saws, reciprocal saws, and jigsaws), electric chainsaws that drive a saw chain with electric power, electric impact hammersthat drive an impact hammer with electric force (including tackers),electric garden tools that drive a cutter with electric power (includinghedge trimmers, grass trimmers, manual push lawn mowers, and brushcutters), electric blowers that drive an air blowing fan with electricpower, electric vacuums that drive a vacuum fan (including electriccleaners), and the like.

According to the electric wheeled apparatus of the present teachings,the user need not provide a dedicated battery pack or charger for theelectric wheeled apparatus. The user can use the battery pack in anelectric bicycle that the user prepared for use in the electric powertool. In another case, the user can use the battery pack that the userprepared for the electric bicycle in the electric power tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an electric bicycle of one embodiment.

FIG. 2 shows a battery pack for an electric power tool.

FIG. 3 shows the electric power tool that removably receives the batterypack.

FIG. 4 shows the electric power tool in which the battery pack isattached.

FIG. 5 shows a charger that recharges the battery pack.

FIG. 6 shows a battery interface of Embodiment 1.

FIG. 7 shows the battery pack attached to the battery interface.

FIG. 8 shows the battery interface of Embodiment 1 in which the batterypack is attached.

FIG. 9 shows a block diagram that shows an electrical layout of anelectric bicycle.

FIG. 10 shows a battery interface of Embodiment 2, in which a pluralityof battery packs is removably receivable.

FIG. 11 shows a supply circuit of Embodiment 2 that connects theplurality of battery packs in parallel.

FIG. 12 shows a supply circuit of Embodiment 2 that electricallydisconnects some of the battery packs.

FIG. 13 shows a situation in which only one battery pack is used inEmbodiment 2.

FIG. 14 shows a modification of the supply circuit of Embodiment 2, inwhich a switch circuit has been removed.

FIG. 15 shows a supply circuit of Embodiment 3, in which a plurality ofbattery packs is connected in series.

FIG. 16 shows a modification of the supply circuit of Embodiment 3, inwhich a selection circuit has been added.

FIG. 17 shows a situation in which only two battery packs are used inthe modified supply circuit shown in FIG. 16.

FIG. 18 shows a situation in which only one battery pack is used in themodified supply circuit shown in FIG. 16.

FIG. 19 is a side view that schematically shows a carrier cart ofEmbodiment 4.

FIG. 20 is a rear view that schematically shows the carrier cart ofEmbodiment 4.

FIG. 21 is a side view that schematically shows a suitcase of Embodiment5.

FIG. 22 is a rear view that schematically shows the suitcase ofEmbodiment 5.

Fig, 23 is a side view that schematically shows a wheelbarrow ofEmbodiment 6.

FIG. 24 is a side view that schematically shows a modification of thewheelbarrow of Embodiment 6.

FIG. 25 is a side view that schematically shows an electric power mowerof Embodiment 7.

FIG. 26 is a side view that schematically shows an electric powercultivator of Embodiment 8.

FIG. 27 schematically shows a range of use of the battery pack for theelectric power tool.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of the present teachings, the battery interface canreceive a plurality of battery packs for use in electric power tools,including a first battery pack and a second battery pack. According tothis structure, the maximum distance and maximum output of the electricbicycle can be improved by using the plurality of battery packs.

In the aforementioned embodiment, an electric circuit unit may beconfigured such that a first battery pack and a second battery packattached to a battery interface are connected in parallel. In thisconfiguration, electric power can be supplied to an electric motor for along period of time by connecting the plurality of battery packs inparallel. Thus, the maximum usage distance of an electric bicycle (whichis an example of an electric wheeled apparatus) can be lengthened. Inaddition, when the electric circuit unit is configured such that theplurality of battery packs attached to the battery interface areconnected in parallel, the electric circuit unit can electricallyconnect the battery packs attached to the battery interface to anelectric motor. Thus, a user can change the number of battery packsattached to the battery interface e.g. in response to the distance inwhich the electric wheeled apparatus will be used. In other words, whenusage over a short distance is planned, only one battery pack can beattached in the battery interface, and when usage over a long distanceis planned, a plurality of battery packs can be attached to the batteryinterface. By changing the number of battery packs in accordance withthe usage distance, the electric wheeled apparatus can be prevented frombecoming too heavy.

In the aforementioned embodiment, it is preferable that the electriccircuit unit is provided with at least two switching elements and isconfigured capable of electrically disconnecting each of the first andsecond battery packs by turning off a corresponding one of the at leasttwo switching elements. According to this configuration, when one of thefirst and second battery packs has run out of charged power, theelectric circuit can turn off the corresponding one of the switchingelement and prevent the exhausted pack battery pack from beingover-discharged.

In another embodiment, the electric circuit unit may be configuredcapable of electrically connecting the first and second battery packs tothe electric motor one by one. In this configuration, the electriccircuit unit is capable of electrically connecting the first and secondbattery packs to the electric motor independently at different timings.For example, the electric circuit may electrically connect only thefirst battery pack to the electric motor, even when both the first andsecond battery packs are attached to the battery interface. And then,when the first battery pack has run out of charged power, the electriccircuit can electrically connect the second battery pack to the electricmotor in replacement of the first battery pack. According to thisconfiguration, e.g. when a small amount of electric power is consumed bythe electric motor, the charged power of the second battery pack is notconsumed, and later the user do not have to charge the two batterypacks, but to charge only the first battery pack.

In one embodiment of the present teachings, the electric circuit unitmay be configured capable of electrically connecting the first andsecond battery packs in series with the electric motor when the firstand second battery packs are attached to the battery interface. Byconnecting the plurality of battery packs in series, the electriccircuit unit can supply a high voltage to the electric motor, and themaximum output power of the electric wheeled apparatus can be improved.

In one embodiment of the present teachings, the electric wheeledapparatus may be an electric bicycle, and further comprise pedals towhich a user applies force, and a user force transmission that transmitsthe force applied to the pedals to at least one wheel. In this electricbicycle, even when all of the electric power of the battery pack hasbeen used by the electric power tool, the user can travel with theelectric bicycle by pumping the pedals similarly to a normal bicycle.Furthermore, the electric bicycle may also be configured to generateelectricity by the electric motor during the user travel by pumping thepedals, and thus recharge the battery pack. Here, the electric bicycleis not limited to a two-wheeled vehicle, and includes unicycles andtricycles. The number of wheels of the electric bicycle is notparticularly limited.

In the aforementioned electric bicycle, the electric circuit unitpreferably adjusts the electric force supplied to the electric motorfrom the battery pack in response to the force applied to the pedals bythe user. In this configuration, the user can be sufficiently assistedwhen starting out or climbing a hill, and a speed of the electricbicycle can be prevented from becoming excessive when on a flat terrain.

In another embodiment of the present teachings, the electric wheeledapparatus may be configured such that one or a plurality of batterypacks having a nominal voltage of 14.4 volts, battery packs having anominal voltage of 18 volts, and battery packs having a nominal voltageof 36 volts, can be used. Furthermore, the electric wheeled apparatusmay also be configured such that battery packs having a nominal voltagethat exceed 100 volts can be used. The output voltage of the batterypacks is not particularly limited. The electric wheeled apparatus mayalso be configured such that only battery packs having a predeterminedoutput voltage can be used, or may be configured such that a pluralityof battery pack types having different output voltages can be used.

According to another embodiment of the present teachings, the electricwheeled apparatus can have front and rear wheels. However, the electricwheeled apparatus is not limited to two wheels, and may have only onewheel (a unicycle) or three wheels or more. With an electric wheeledapparatus having a plurality of wheels, the electric motor may applytorque to only one wheel, or the electric motor can apply torque to aplurality of wheels.

In another embodiment of the present teachings, the electric wheeledapparatus is an electric bicycle having a front wheel and a rear wheel,and in which the force applied by the user to the pedals is transmittedto the rear wheel via a chain. In addition, the torque output by theelectric motor is transmitted to the rear wheel via a drive chain.However, the electric bicycle may be configured such that the torqueoutput by the electric motor is applied to the front wheel. In thiscase, the electric motor can e.g. be arranged on a hub of the frontwheel. The wheel to which the force from the user is applied, and thewheel to which the torque of the electric motor is applied, may be thesame or may be different.

According to another embodiment of the present teachings, the electricwheeled apparatus may be configured such that the battery interface canremovably receive battery packs having a variety of different shapes.With this configuration, an adaptor may be interposed between thebattery interface and the battery packs.

In another embodiment of the present teachings, the battery interfacehas at least one pack receiving portion. A connector provided on thebattery pack is removably receivable on the pack receiving portion ofthe battery interface. Here, the connector on the battery pack is alsoremovably receivable on the pack receiving portion provided on anelectric power tool.

In another embodiment of the present teachings, the electric wheeledapparatus can be a suitcase or electric power tool case that comprises acase main body that contains an object, wheels provided on the case mainbody, and an electric motor that drives the wheels. In this case, it ispreferable that the attachment and removal of the battery pack withrespect to the battery interface be possible from only the inside of thecase main body.

Representative, non-limiting examples of the present invention will nowbe described in further detail with reference to the attached drawings.This detailed description is merely intended to teach a person of skillin the art further details for practicing preferred aspects of thepresent teachings and is not intended to limit the scope of theinvention. Furthermore, each of the additional features and teachingsdisclosed below may be utilized separately or in conjunction with otherfeatures and teachings to provide improved electric wheeled apparatus.

Moreover, combinations of features and steps disclosed in the followingdetail description may not be necessary to practice the invention in thebroadest sense, and are instead taught merely to particularly describerepresentative examples of the invention. Furthermore, various featuresof the above-described and below-described representative examples, aswell as the various independent and dependent claims, may be combined inways that are not specifically and explicitly enumerated in order toprovide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

(Embodiment 1)

An electric bicycle 10 of Embodiment 1 will be described with referenceto the drawings. The electric bicycle 10 is an example of an electricbicycle in which the present teachings have been realized. As shown inFIG. 1, the electric bicycle 10 has a front wheel 22 and a rear wheel 36rotatably provided on a main body 14. The main body 14 has a stem 18that is pivotable. The stem 18 includes a fork 20 that rotatablysupports the front wheel 22, and a handle 16 that is grasped by a user.Brake levers (not illustrated in the drawings) are provided on both endsof the handle 16.

The electric bicycle 10 has a saddle 12 on which a user sits, and crankpedals 30 on which the user applies pedal force. The crank pedals 30have a shaft 28 that is rotatably supported by the main body 14.

The electric bicycle 10 comprises a drive sprocket 26 that isconcentrically fixed on the central shaft 28 of the crank pedals 30, adriven sprocket 38 that is concentrically fixed on the rear wheel 36,and a chain 32 that extends around both the drive sprocket 26 and thedriven socket 38. The drive sprocket 26, the driven sprocket 38, and thechain 32 compose a user force transmission that transmits the forceapplied to the crank pedals 30 to the rear wheel 36. Here, the userforce transmission is not limited to a transmission mechanism that usesthe chain 32; alternatively, may be a transmission mechanism that uses atransmission belt, or may be a transmission mechanism that uses arotation shaft.

The electric bicycle 10 comprises an electric assist unit 50. Theelectric assist unit 50 has a battery interface 54, an electric circuitunit 56, and an electric motor 58 installed inside a case 51 having anopenable cover 52. The case 51 is closed by closing the cover 52, whichprevents the intrusion of moisture and dirt. The electric motor 58 is aDC brushless motor having an output of 240 watts. Note that the shape ofthe electric motor 58 is not particularly limited. A battery pack 100 isremovably received in the battery interface 54. Although additionaldetails will be provided below, the battery pack 100 is a battery packthat is used in an electric power tool. The electric circuit unit 56comprises a circuit for connecting the battery interface 54 with theelectric motor 58, and controlling the operation of the electric motor58. In addition, the electric bicycle 10 also includes a user forcesensor 24 that serves to measure the force applied to the crank pedals30 by the user, and a speed sensor 34 that serves to measure the speedof the electric bicycle 10. Note that the user force sensor 24 uses adistortion sensor that measures the distortion produced by the drivesprocket 26, and the speed sensor 34 uses a pulse counter that measuresthe number of rotations of the rear wheel 36.

Next, the battery pack 100 will be described with reference to FIGS. 2,3 and 4. The battery pack 100 used by the electric bicycle 10 of thepresent embodiment is a battery pack 100 that is used in an electricpower tool 200. Here, an electric hand drill is illustrated in FIGS. 3and 4 as an example of the electric power tool 200. The battery pack 100is a slide-type battery pack, and an engagement portion 104 is providedon the upper surface of a housing 102. The housing 202 of the electricpower tool 200 includes a pack receiving portion 204 in which theengagement portion 104 of the battery pack 100 is received. The packreceiving portion 204 of the electric power tool 200 removably receivesthe battery pack 100, and has a plurality of terminals (not illustratedin the drawings) that electrically connect the attached battery pack100.

The battery pack 100 is equipped with a plurality of secondary batterycells (not illustrated in the drawings). The secondary battery cells arelithium ion secondary battery cells.

The battery pack 100 is equipped with 10 secondary battery cells, inwhich groups of two secondary battery cells are connected in paralleland these 5 groups are connected together in series. The lithium ionsecondary battery cells have an output voltage (nominal) of 3.6 volts,and the output voltage (nominal) of the battery pack 100 of the presentembodiment is 18 volts. The electric power tool 200 can drive anelectric motor provided therein by the electric power supplied from theattached battery pack 100.

Here, the type of secondary battery cells in the battery pack 100 usedin the electric bicycle 10 is not particularly limited. In addition, thenumber of battery cells provided in the battery pack 100 is notparticularly limited, and there is no particular limit on the outputvoltage of the battery pack 100. The electric bicycle 10 can, forexample, also use battery packs having an output voltage of 14.4 volts,18 volts, or 36 volts, and can also use battery packs whose outputvoltage exceeds 100 volts. Design modifications may be made in responseto the voltage of the battery pack 100 that is needed.

As shown in FIG. 2, the engagement portion 104 of the battery pack 100has a pair of ribs 120 that extends parallel to each other, and anengagement hook 122 that is urged by an elastic force. The engagementportion 104 is provided with a positive terminal 112, a negativeterminal 116, a temperature terminal 108, and communication terminals106. The positive terminal 112, negative terminal 116, and temperatureterminal 108 are housed in the interior of slits 114, 110, and 118. Thepositive terminal 112 and the negative terminal 116 are connected to thesecondary battery cells housed in the battery pack 100, The temperatureterminal 108 is connected to a thermistor (not illustrated in thedrawings) that is housed in the battery pack 100, and will output avoltage in response to the temperature of the secondary battery cells.The communication terminals 106 are connected to a controller (notillustrated in the drawings) that is housed in the battery pack 100.

As shown in FIG. 5, the battery pack 100 can be repeatedly recharged bya charger 300. A housing 302 of the charger 300 is provided with a packreceiving portion 304 that receives the engagement portion 104 of thebattery pack 100. The pack receiving portion 304 is provided with avariety of terminals and connectors that electrically connect to thebattery pack 100, and a terminal cover 306 that protects these terminalsand connectors. The charger 300 removably receives the battery pack 100,and charges the battery pack 100 attached therein. The charger 300 canadjust the charge current supplied to the battery pack 100 in responseto the temperature and voltage of the secondary battery cells of thebattery pack 100.

We now return to the description of the electric bicycle 10. As shown inFIGS. 6, 7 and 8, the pack receiving portion 60 that receives thebattery pack 100 is formed in the battery interface 54 of the electricbicycle 10. The pack receiving portion 60 comprises a pair of ribs 62that engages with the engagement portion 104 of the battery pack 100 andan engagement hole 65. The pair of ribs 62 of the pack receiving portion60 engages with the pair of ribs 120 provided in the battery pack 100,and the engagement hole 65 of the pack receiving portion 60 receives theengagement hook 122 of the battery pack 100. The pack receiving portion60 removably receives the engagement portion 104 of the battery pack100, and can firmly grasp the housing 102 of the attached battery pack100.

A connector plug 64 is provided on the pack receiving portion 60. Theconnector plug 64 electrically connects the attached battery pack 100with the pack receiving portion 60. The connector plug 64 comprises apositive connection terminal 66 that connects to the positive terminal112 of the battery pack 100, a negative connection terminal 68 thatconnects to the negative terminal 116 of the battery pack 100, and acommunication connector 70 that connects to the communication terminals106 of the battery pack 100.

Next, the electrical configuration of the electric bicycle 10 will bedescribed with reference to FIG. 9. As shown in FIG. 9, the electriccircuit unit 56 comprises a supply circuit 72 and a controller 74. Thesupply circuit 72 electrically connects the connector plug 64 and theelectric motor 58, and supplies electric power from the battery pack 100connected to the connector plug 64 to the electric motor 58. The supplycircuit 72 comprises a positive electric power line 76 that electricallyconnects the positive terminal connector terminal 66 of the connectorplug 64 to the electric motor 58, a negative electric power line 78 thatelectrically connects the negative terminal connector terminal 68 of theconnector plug 64 to the electric motor 58, and an electric poweradjustment circuit 77 that is provided on the positive electric powerline 76. The electric power adjustment circuit 77 is a circuit thatadjusts the electric power supplied from the battery pack 100 to theelectric motor 58. The supply circuit 72 adjusts the electric powersupplied from the battery pack 100 to the electric motor 58 by using theelectric power adjustment circuit 77 in accordance with a command fromthe controller 74. Here, the electric power adjustment circuit 77 has afield effect transistor, and adjusts the electric power supplied to themotor 58 by controlling the duty ratio of the field effect transistor.

The controller 74 is configured to use a microcomputer. The controller74 is connected to the user force sensor 24, the speed sensor 34, and acommunication connector 70 of the connector plug 64. The controller 74determines a target value of the electric force supplied to the electricmotor 58 in response to the measurement results of the user force sensor24 and the speed sensor 34. In other words, it will determine the torqueapplied to the rear wheel 36 by the electric motor 58. Then, thecontroller 74 will use the target value of the determined electric powerto provide a command to the supply circuit 72. The controller 74 will,for example, increase the target value of the electric power supplied tothe electric motor 58 as the force detected by the user force sensor 24increases. In this configuration, the user can be greatly helped whenstarting out or climbing a hill. In addition, the controller 74 willlower the target value of the electric power supplied to the electricmotor 58 as the speed detected by the speed sensor 34 increases. In thisconfiguration, excessive speed can be prevented with the electricbicycle 10. The user can receive an appropriate amount of assistancefrom the electric motor 58, and can easily travel a route that is a longdistance or has a high vertical interval by the electric bicycle 10.

The electric bicycle 10 of the present embodiment can use the batterypack 100 for the electric power tool 200 as a power source, and does notneed a dedicated battery pack or charger. The user of the electric powertool 200 can also effectively use the battery pack for the electricpower tool 200 on the electric bicycle 10. In addition, assuming thatthe user also uses the electric bicycle 10, if the user owns a largenumber of battery packs 100 for use with the electric power tool 200,the user can also use the electric power 200 for a long period of timeby sequentially using these battery packs 100. In addition, in the eventthat the user is to carry the electric power tool 200 and ride theelectric bicycle 10 to a work site, the user can use the battery pack100 when travelling to the work site and when working at the work site.Different from a combination of a conventional electric bicycle andelectric power tool, since it is not necessary to install separatededicated battery packs for the electric bicycle and the electric powertool respectively, the number of objects carried when travelling to thework site can be reduced. Furthermore, the irritation of managing aplurality of types of battery packs will also be eliminated.

(Embodiment 2)

An electric bicycle of Embodiment 2 will be described. The electricbicycle of Embodiment 2 is the electric bicycle 10 of Embodiment 1, inwhich the battery interface 54 and supply circuit 72 have been changed.Because the configuration of the other aspects of the electric bicycleof Embodiment 2 has not been particularly changed, duplicate descriptionwill be omitted by applying the same reference numbers.

As shown in FIG. 10, the electric bicycle 10 of Embodiment 2 is providedwith three pack receiving portions 60 a, 60 b, 60 c in the batteryinterface 54, and removably receive a maximum of three battery packs 100a, 100 b, 100 c (hereinafter sometimes abbreviated as battery packs100). Similar to Embodiment 1, each pack receiving portion 60 a, 60 b,60 c is provided with a pair of ribs 62 a, 62 b, 62 c and a connectionplug 64 a, 64 b, 64 c. Each connection plug 64 a, 64 b, 64 c comprises apositive terminal connection terminal 66 a, 66 b, 66 c, a negativeterminal connection terminal 68 a, 68 b, 68 c, and a communicationconnector 70 a, 70 b, 70 c. Here, the battery interface 54 may also beconfigured to removably receive two battery packs 100, and mayalternatively be configured to removably receive a number of batterypacks 100 in excess of three.

The changed portions of the supply circuit 72 will be described withreference to FIG. 11. As shown in FIG. 11, the supply circuit 72 ofEmbodiment 2 can connect the plurality of attached battery packs 100 inparallel with the electric motor 58. In other words, with the supplycircuit 72 of Embodiment 2, the positive terminal connection terminals66 a, 66 b, 66 c of each connection plug 64 a, 64 b, 64 c are connectedto the positive electric power line 76, and the negative terminalconnection terminals 68 a, 68 b, 68 c of each connection plug 64 a, 64b, 64 c are connected to the negative electric power line 78.

In the present embodiment, electric power can be supplied to theelectric motor 58 by the three battery packs 100 connected in parallel.Thus, it will be possible to supply a great deal of electric power tothe electric motor 58, and the cruising time and cruising distancetravelled by the electric bicycle 10 can be increased.

Furthermore, in the supply circuit 72, the positive terminal connectionterminals 66 a, 66 b, 66 c of the respective connection plugs 64 a, 64b, 64 c are connected to the positive power line 76 via switch circuits80 a, 80 b, 80 c, respectively. The switch circuits 80 a, 80 b, 80 c areeach switched on and off by a command from the controller 74. As shownin FIG. 12, the supply circuit 72 can electrically disconnect some ofthe three attached battery packs 100 from the electric motor 58 byturning off some of the switch circuits 80 a, 80 b, 80 c. Accordingly,for example, when the charge state of one battery pack 100 a has droppedbelow a predetermined threshold, the supply circuit 72 can turn off thecorresponding switch circuit 80 a in order to prevent the over-dischargeof the battery pack 100 a. The controller 74 can estimate the chargestate of each battery pack 100 by monitoring the output voltage of eachbattery pack 100. Then, the controller 74 can selectively turn off theswitch circuits 80 a, 80 b, 80 c based upon the estimate charge state ofthe battery packs 100. Note that another configuration is also possiblein which a display unit (not illustrated in the drawings) is providedthat displays the charge state of each battery pack 100 to the user, andthe user will decide by him or her self to switch the switch circuits 80a, 80 b, 80 c by an operation panel (not illustrated in the drawings).

Alternatively, the supply circuit 72 can also sequentially switch amongthe three attached battery packs 100 to a battery pack 100 that willsupply electric power to the electric motor 58. In other words, thesupply circuit 72 will first connect only the first battery pack 100 ato the electric motor 58, and supply electric power from only the firstbattery pack 100 a to the electric motor 58. If the charge state of thefirst battery pack 100 a is depleted, the supply circuit 72 willelectrically disconnect the first battery pack 100 a, connect the secondbattery pack 100 b to the electric motor 58, and supply electric powerfrom only the second battery pack 100 b to the electric motor 58. Then,if the charge state of the second battery pack 100 b is depleted, thesupply circuit 72 will electrically disconnect the second battery pack100 a, connect the third battery pack 100 c to the electric motor 58,and supply electric power from only the third battery pack 100 c to theelectric motor 58. With this method, in the same way as when supplyingelectric power from three battery packs 100 simultaneously, the cruisingtime and cruising distance of the electric bicycle 10 can be increased.Furthermore, according to this method, in the event that the electricbicycle 10 is to be used for a short distance and amount of time, thesecond and third battery packs 100 b, 100 c can be stored without beingdischarged, and the number of battery packs 100 to be charged thereaftercan be reduced.

The switching of the aforementioned battery packs 100 can be performedby the controller 74. In this case, the controller 74 will monitor theoutput voltage of the first battery pack 10 connected to the electricmotor 58, and at the point at which the output voltage of the firstbattery pack 100 a falls to a predetermined value, the controller 74will turn off the corresponding switch circuit 80 a, and turn on theswitch circuit 80 a corresponding to the second battery pack 100 b. Byswitching this procedure, the controller 74 can sequentially switch thebattery pack 100 that supplies electric power to the electric motor 58.However, the electric bicycle 10 may also be configured such thatswitching the battery pack 100 does not depend on the controller 74, butinstead will be determined by the user by an operation panel (notillustrated in the drawings).

Here, when for example the user continues to climb a long incline, and agreat deal of electric power continues to be supplied from battery pack100 a to the electric motor 58, the temperature of the battery pack 100a may abnormally increase. In this type of situation, the electricbicycle 10 will preferably temporarily connect the other battery packs100 b, 100 c to the electric motor 58. In other words, the electricbicycle 10 will preferably connect the battery pack 100 a that isalready being used to the other battery packs 100 b, 100 c in parallel.In this configuration, the current flowing from the battery pack 100acan be reduced, and the temperature increase of the battery pack 100 acan be largely prevented. Note that the temperature of the battery packs100 can be easily monitored by using the temperature terminals 108 ofthe battery packs 100. The controller 74 of the electric circuit 56 canselectively switch the three switch circuits 80 a, 80 b, 80 c of thesupply circuit 72, based upon the temperature data received from thebattery packs 100. Alternatively, the switch circuits 80 a, 80 b, 80 cmay be switched by the user.

As shown in FIG. 13, only one battery pack 100 a can be attached andused with the electric bicycle 10 of Embodiment 2. It is not necessaryfor the three battery packs 100 a, 100 b, 100 c to be attached. Evenwhen only one battery pack 100 a is attached, electric power will besupplied from that battery pack 100 a to the electric motor 58, andassistance will be provided by the torque output from the electric motor58. Thus, the user can change the number of battery packs 100 attachedto the electric bicycle 10 in response to the time and distance the userintends to travel by the electric bicycle 10. By installing only thenumber of battery packs 100 that is needed, a needless increase in theweight of the electric bicycle 10 can be avoided.

FIG. 14 is a modification of the supply circuit 72 described inEmbodiment 2. As shown in FIG. 14, the switch circuits 80 a, 80 b, 80 cdo not necessarily need to be provided in the supply circuit 72. Even ifthe switch circuits 80 a, 80 b, 80 c are not provided, the attachedbattery packs 100 a, 100 b will be connected in parallel to the motor58. The user can change the number of battery packs 100 a, 100 b, 100 cattached to the electric bicycle 10 in response to the time and distancethe user intends to travel by the electric bicycle 10.

(Embodiment 3)

An electric bicycle of Embodiment 3 will be described. The electricbicycle of Embodiment 3 is the electric bicycle 10 of Embodiment 2, inwhich primarily the supply circuit 72 has been changed. Because theconfiguration of the other aspects of the electric bicycle of Embodiment2 have not been particularly changed, duplicate description will beomitted by applying the same reference numbers.

As shown in FIG. 15, the supply circuit 72 of Embodiment 3 can connectthe three attached battery packs 100 a, 100 b, 100 c in series with theelectric motor 58. In other words, with the supply circuit 72 ofEmbodiment 3, the negative terminal connection terminal 68 a of thefirst connection plug 64 a is connected to the positive terminalconnection terminal 66 b of the second connection plug 64 b via a firstconnection line 82 a, and the negative terminal connection terminal 68 bof the second connection plug 64 b is connected to the positive terminalconnection terminal 66 c of the third connection plug 64 c via a secondconnection line 82 b.

With the electric bicycle 10 of Embodiment 3, a high voltage can beapplied to the electric motor 58 by three battery packs 100 connected inseries. A large current can flow to the electric motor 58, and thetorque output by the electric motor 58 can be improved. According to theelectric bicycle 10 of Embodiment 3, the user can receive a largerauxiliary force from the electric motor 58, and can easily climb evensteep inclines.

FIG. 16 is a modification of the supply circuit 72 described inEmbodiment 3. Two selection circuits 84 a, 84 b are added to the supplycircuit 72 shown in FIG. 16. The two selection circuits 84 a, 84 b areeach operated by a command from the controller 74. The first selectioncircuit 84 a is provided between the first connection line 82 and thenegative electric power line 78. The first selection circuit 84 a is acircuit that selectively connects the negative terminal connectionterminal 68 a of the first connection plug 64 a to either the positiveterminal connection terminal 66 b of the second connection plug 64 b orthe negative electric power line 78. The second selection circuit 84 bis provided between the second connection line 82 b and the negativeelectric power line 78. The second selection circuit 84 b is a circuitthat selectively connects the negative terminal connection terminal 68 bof the second connection plug 64 b to either the positive terminalconnection terminal 66 c of the third connection plug 64 c or thenegative electric power line 78. Each selection circuit 84 a, 84 b maye.g. be configured by a plurality of semiconductor switches.

As shown in FIG. 16, the supply circuit 72 having the selection circuits84 a, 84 b can connect the three battery packs 100 a, 100 b, 100 c tothe electric motor 58 in series when the three battery packs 100 a, 100b, 100 c are attached. In addition, as shown in FIG. 17, when twobattery packs 100 a, 100 b have been attached, the supply circuit 72 canconnect the two battery packs 100 a, 100 b to the electric motor 58 inseries by switching the second selection circuit 84 b. Then, as shown inFIG. 18, when only one battery pack 100 a is attached, the supplycircuit 72 can correctly connect the one attached battery pack 100 a tothe electric motor 58 by further switching the first selection circuit84 a. The user can change the number of battery packs 100 a, 100 b, 100c attached to the electric bicycle 10 in response to the auxiliary forcerequested by the electric motor 58. The switching of the aforementionedselection circuit 84 a, 84 b is performed by a command from thecontroller 74. The controller 74 will detect the number of battery packs100 attached to the battery interface 54 by monitoring the voltagesgenerated by the connection plugs 64 a, 64 b, 64 c. Then, the controller74 will operate each selection circuit 84 a, 84 b based upon the numberof battery packs 100 detected. Note that the selection circuits 84 a, 84b may also be configured such that the user can operate them by anoperation panel (not illustrated in the drawings).

The teachings disclosed in the aforementioned embodiments are notlimited to the electric bicycle, and can also be applied to a variety ofother electric wheeled apparatuses. Without being limited to thespecific type of electric wheeled apparatus, an electric wheeledapparatus that can use the battery packs from electric power tools canmore effectively utilize the battery packs, and can reduce the burden onthe user managing the battery packs. In particular, an electricmotorcycle capable of running only on torque from the electric motor canemploy much of the teachings disclosed in the present embodiment,because many portions thereof resemble the structure and function of anelectric bicycle.

In addition, although a combination of the electric hammer drill and theelectric bicycle was described in the aforementioned embodiment, theteachings of the present embodiment can effectively employ a combinationof other types of electric power tools and other types of electricwheeled apparatuses. For example, it is effective to employ theteachings of the present embodiment in a combination of an electric golfcart (a type of electric wheeled apparatus) and an electric garden tool.In other words, if the battery pack for the electric power tool can beused in the electric golf cart, the battery pack for the electric powertool can be effectively utilized. The battery pack can be used in theelectric golf cart during golf course business hours, and the batterypack can be used in the electric garden tool outside the golf coursebusiness hours to manage the grass and trees thereon.

In addition, the teachings described in Embodiments 2 and 3 that use aplurality of battery packs are not limited to the use of battery packsfor electric power tools, and the use of other battery packs is alsoeffective. In other words, even with an electric wheeled apparatus thatuses a dedicated battery pack, the teachings described in Embodiments 2and 3 can be usefully employed.

In addition, by combining the teachings of Embodiments 2 and 3, it willalso be possible to implement an electric circuit unit that canselectively form a circuit that connects the, plurality of attachedbattery packs in parallel, and a circuit that connects the plurality ofattached battery packs in series. Alternatively, it will also bepossible to implement an electric circuit unit that will divide theplurality of attached battery packs into a plurality of groups, connectthe battery packs in each group in parallel, and then connect the groupof battery packs connected in parallel in series.

(Embodiment 4)

An electric carrier cart 400 of Embodiment 4 will be described withreference to FIGS. 19 and 20. The electric carrier cart 400 is one typeof electric carrier that is used to haul objects. As shown in FIGS. 19and 20, the electric carrier cart 400 has a cart main body 414 and apair of wheels 436 that are rotatably provided on the cart main body414.

The cart main body 414 has a luggage platform 412 on which luggage isloaded, and a rear frame 418 that extends upward from the luggageplatform 412. A grip 416 for the user to grasp is provided on the upperend of the rear frame 418. A grip sensor 424 for detecting whether ornot the user is grasping the grip 416 is provided on the grip 416. Apair of wheels 436 is provided on the luggage platfotiii 412 of the cartmain body 414. The pair of wheels 436 is arranged concentrically, withthe luggage platform 412 interposed therebetween. When the user graspsthe grip 416 and tilts the cart main body 414 toward the rear frame 418,the electric carrier cart 400 will be supported by only the pair ofwheels 436. When the user pulls (or pushes) the carrier cart 400 in thisstate, the electric carrier cart 400 will move by rotating the pair ofwheels 436.

The carrier cart 400 further comprises two battery interfaces 454, anelectric circuit unit 456 that is connected to the two batteryinterfaces 454, and a pair of electric motors 458 that are connected tothe electric circuit unit 456. Here, each battery interface 454 issubstantially the same as the battery interface 54 shown in FIG. 6, andremovably receive battery packs 100 for the electric power tool 200. Thebattery interfaces 435 and the electric circuit unit 456 are housed inthe luggage platform 412, and an openable cover 452 for attaching andremoving the battery packs 100 is provided on the luggage platform 412.

The battery interfaces 454 are arranged such that the attached batterypacks 100 are located between the pair of wheels 436. According to thistype of arrangement, the center of gravity of the battery packs 100 willnot greatly shift even when the cart main body 414 is tilted around thepair of wheels 436. Thus, the user cannot particularly feel the weightof the battery packs 100, and can pull (or push) the electric carriercart 400 when in the tilted state. Here, it is not necessary to positionall of the attached battery packs 100 in between the pair of wheels 436,but it is preferable that the center of gravity of the battery packs 100is located in between the pair of wheels 436.

The pair of electric motors 458 is each integrated with a correspondingone of the pair of wheels 436. In other words, each electric motor 458is referred to as an in-wheel type of electric motor. When in-wheel typeelectric motors 458 are employed, the electric carrier cart 400 can bepulled (or pushed) in the tilted state without the user particularlyfeeling the weight of the electric motors 458. Electric power issupplied from the battery packs 100 attached to the battery interfaces454 to each electric motor 458 via the electric circuit unit 456. Eachelectric motor 458 applies torque to the integrated wheels 436, andassists the user to pull (or push) the carrier cart 400. Here, theaforementioned grip sensor 424 is connected to the electric circuit unit456, and the electric circuit unit 456 will supply electric power toeach electric motor 458 only while the user is grasping the grip 416.Thus, movement of the electric carrier cart 400 that is not intended bythe user will be prohibited. In addition, the electric circuit unit 456preferably adjusts the electric power supplied to each electric motor458 in response to the force applied by the user on the grip 416.

The electric carrier cart 400 do not need dedicated battery packs, andcan use the battery packs 100 of the electric power tool 200 as a powersource. Because of that, the user can effectively use the electricbattery packs 100 in his or her possession in both the electric powertool 200 and the electric carrier cart 400. Because the battery packs100 designed for use in the electric power tool 200 have a high output,they can sufficiently function as a power source for the electriccarrier cart 400.

(Embodiment 5)

An electric suitcase 500 of Embodiment 5 will be described withreference to FIGS. 21 and 22. The electric suitcase 500 is one type ofelectric carrier that is used to haul objects. As shown in FIGS. 21 and22, the electric suitcase 500 has a case main body 514 and a pair ofwheels 536 that is rotatably provided on the case main body 514.

The case main body 514 has a housing 514 that houses objects, and a grip516 that is arranged on the upper portion thereof. A grip sensor 524 fordetecting whether or not the user is grasping the grip 516 is providedon the grip 516. A pair of wheels 536 is provided on the lower portionof the case main body 514. The pair of wheels 536 is arrangedconcentrically, with the case main body 514 interposed therebetween.When the user grasps the grip 516 and tilts the case main body 514toward the grip 518, the electric suitcase 500 will be supported by onlythe pair of wheels 536. When the user pulls (or pushes) the electricsuitcase 500 in this state, the electric suitcase 500 will move byrotating the pair of wheels 436.

The electric suitcase 500 further comprises two battery interfaces 554,an electric circuit unit 556 that is connected to the two batteryinterfaces 554, and a pair of electric motors 558 that is connected tothe electric circuit unit 556. Each battery interface 554 issubstantially the same as the battery interface 54 shown in FIG. 6, andremovably receive battery packs 100 for the electric power tool 200. Thebattery interfaces 554 and the electric circuit unit 556 are housed inthe case main body 514. The attachment and removal of the battery packs100 with respect to the battery interfaces 554 is only possible frominside the case main body 514, and the case main body 514 must be open.Thus, the battery pack 100 can be prevented from being unintentionallylost, without for example locking the case main body 514.

The battery interfaces 554 are arranged such that the attached batterypacks 100 are located between the pair of wheels 436. According to thistype of arrangement, the center of gravity of the battery packs 100 willnot greatly shift even when the case main body 514 tilts around the pairof wheels 536. Thus, the user cannot particularly feel the weight of thebattery packs 100, and can pull (or push) the electric suitcase 500 whenin the tilted state. Here, all attached battery packs 100 are positionedbetween the pair of wheels 536. Preferably, the center of gravity of thebattery packs 100 is positioned between the pair of wheels 536.

The pair of electric motors 558 is each integrated with a correspondingone of the pair of wheels 536. In other words, each electric motor 558is referred to as an in-wheel type of electric motor. When in-wheel typeelectric motors 558 are employed, the electric suitcase 500 can bepulled (or pushed) in the tilted state without the user particularlyfeeling the weight of the electric motors 558. Electric power issupplied from the battery packs 100 attached to the battery interfaces558 to each electric motor 556 via the electric circuit unit 554. Eachelectric motor 558 applies torque to the integrated wheels 536, andassists the user to pull (or push) the electric suitcase 500. Here, theaforementioned grip sensor 524 is connected to the electric circuit unit556, and the electric circuit unit 556 will supply electric power toeach electric motor 558 only while the user is grasping the grip 516.Thus, movement of the electric suitcase 500 that is not intended by theuser will be prohibited. Here, the electric circuit unit 556 preferablyadjusts the electric power supplied to each electric motor 558 inresponse to the force applied by the user on the grip 516.

The electric suitcase 500 does not need dedicated battery packs, and canuse the battery packs 100 of the electric power tool 200 as a powersource. Because of that, the user can effectively use the electricbattery packs 100 in his or her possession in both the electric powertool 200 and the electric suitcase 500. Because the battery packs 100designed for use in the electric power tool 200 have a high output, theycan sufficiently function as a power source for the electric suitcase500. In addition, because the battery packs 100 designed for use in theelectric power tool 200 have superior shock resistance, those functionscan be maintained without being damaged even if, for example, theelectric suitcase 500 receives a shock on a conveyor or turntable at theairport.

(Embodiment 6)

A wheelbarrow 600 of Embodiment 6 will be described with reference toFIG. 23. The wheelbarrow 600 is one type of electric carrier that isused to transport objects, and is one example of an electric wheeledapparatus realized by the present teachings. The wheelbarrow 600 is alsoreferred to as a wheelbarrow, a construction wheelbarrow, or a cat car.As shown in FIG. 23, the wheelbarrow 600 has a main body 614, and onewheel 636 rotatably provided on the main body 614.

The main body 614 has a load portion 612 in which dirt, sand, etc. isloaded, and a pair of grips 616 that are arranged on the rear portionthereof (the right side in FIG. 23). Grip sensors (not illustrated inthe drawings) for detecting whether or not the user is grasping thegrips 616 are provided on the grips 616. The wheel 636 is arranged onthe front portion of the main body 614 (the left side in FIG. 23). Whenthe user grasps and raises the grips 616, the wheelbarrow 600 will besupported only by the wheel 536. When the user pushes the wheelbarrow600 in this state, the wheelbarrow 600 will move by rotating the wheel636.

The wheelbarrow 600 further comprises a battery interface 654, anelectric circuit unit 656 that is connected to the battery interface654, and an electric motor 658 that is connected to the electric circuitunit 656. The battery interface 654 is substantially the same as thebattery interface 54 shown in FIG. 6, and removably receives a batterypack 100 that is used in the electric power tool 200. The batteryinterfaces 654 and the electric circuit unit 656 are housed in anenclosed case 651 having an openable cover 652.

The electric motor 658 is connected to the wheel 636 via a drive shaft632 having a clutch 626. Electric power is supplied from the batterypack 100 attached to the battery interface 654 to the electric motor 658via the electric circuit unit 656. The electric motor 658 will applytorque to the wheel 636 and assist the user pushing the wheelbarrow 600.Here, the aforementioned grip sensors are connected to the electriccircuit unit 656, and the electric circuit unit 656 will supply electricpower to the electric motor 658 only while the user is grasping thegrips 616. Thus, movement of the electric wheelbarrow 600 that is notintended by the user will be prohibited. Here, the electric circuit unit656 preferably adjusts the electric power supplied to the electric motor658 in response to the force applied by the user on the grips 616.

The electric wheelbarrow 600 does not need a dedicated battery pack, andcan use the battery pack 100 of the electric power tool 200 as a powersource. Because of that, the user can effectively use the electricbattery packs 100 in his or her possession in both the electric powertool 200 and the wheelbarrow 600. Because the battery packs 100 designedfor use in the electric power tool 200 have a high output, they cansufficiently function as a power source for the wheelbarrow 600.

FIG. 24 shows a modified wheelbarrow 602. As shown in FIG. 24, anin-wheel type electric motor 658 is employed in the wheelbarrow 602, andthe electric motor 658 is integrated with the wheel 636. When anin-wheel type electric motor 658 is employed, the wheelbarrow 600 can bepushed in a state in which the grips 616 are raised without the userparticularly feeling the weight of the electric motor 658.

(Embodiment 7)

An electric power mower 700 of Embodiment 7 will be described withreference to FIG. 25. The electric power mower 700 is one type of anelectric work vehicle that is used to cut grass, and is one example ofthe electric wheeled apparatus realized by the present teachings. Asshown in FIG. 25, the electric power mower 700 has a vehicle body 714, apair of drive wheels 736 rotatably provided on the vehicle body 714, anda pair of driven wheels 737 rotatably provided on the vehicle body 714.

A rotatably supported cutter 722 and a handle 718 are provided on thevehicle body 714. The cutter 722 is provided on the bottom surface ofthe vehicle body 714, and cuts grass by rotating. A grip 716 for theuser to grasp is provided on the handle 718. A grip sensor 724 fordetecting whether or not the user is grasping the grip 716 is providedon the grip 716. The user will grasp the grip 716 and push the electricpower mower 700, and grass will be cut by moving the electric powermower 700 over the grass.

The electric power mower 700 further comprises a battery interface 754,an electric circuit unit 756 that is connected to the battery interface754, and an electric motor 758 that is connected to the electric circuitunit 756. The battery interface 654 is substantially the same as thebattery interface 54 shown in FIG. 6, and removably receives a batterypack 100 that is used in the electric power tool 200. The batteryinterface 754, the electric circuit unit 756, and the electric motor 758are housed in the vehicle body 714.

The electric motor 758 is connected to both the drive wheels 736 and thecutter 722 via transmission belts 732 a, 732 b. Electric power issupplied from the battery pack 100 attached to the battery interface 758to the electric motor 756 via the electric circuit unit 754. In otherwords, the electric motor 758 applies torque to the cutter 722 and thedrive wheels 736, and both rotate the cutter 722 and assist the user topush the electric power mower 700. Here, the aforementioned grip sensor724 is connected to the electric circuit unit 756, and the electriccircuit unit 756 will supply electric power to the electric motor 758only while the user is grasping the grip 716. Thus, movement of theelectric power mower 700 that is not intended by the user will beprohibited. Here, the electric circuit unit 756 preferably adjusts theelectric power supplied to the electric motor 758 in response to theforce applied by the user on the grip 716.

The electric power mower 700 does not need a dedicated battery pack, andcan use the battery packs 100 used with the electric power tool 200 as apower source. Because of that, the user can effectively use the electricbattery packs 100 in his or her possession in both the electric powertool 200 and the electric power mower 700. Because the battery packs 100designed for use in the electric power tool 200 have a high output, theycan sufficiently function as a power source for the electric power mower700.

(Embodiment 8)

An electric power cultivator 800 of Embodiment 8 will be described withreference to FIG. 26. The electric power cultivator 800 is one type ofelectric work vehicle that is used to cultivate soil, and is one exampleof an electric wheeled apparatus realized by the present teachings. Notethat the electric power cultivator 800 is also referred to as amanagement device. As shown in FIG. 26, the electric power cultivator800 has a vehicle body 814, and a pair of wheels 852 rotatably providedon the vehicle body 814.

A rotatably supported cultivating rotor 822, and handles 818 areprovided on the vehicle body 814. The cultivating rotor 822 is providedon the front portion of the vehicle body 814 (the left side in FIG. 26),and cultivates soil by rotating. The handles 818 extend rearward of thevehicle body (the right side in FIG. 26), and grips 816 for the user tograsp are provided on the ends thereof. Grip sensors (not illustrated inthe drawings) for detecting whether or not the user is grasping thegrips 816 are provided on the grips 816. The user will grasp the grips816 and push the electric power cultivator 800, and cultivation will beperformed by running the electric power cultivator 800.

The electric power cultivator 800 further comprises a battery interface854, an electric circuit unit 856 that is connected to the batteryinterface 854, and an electric motor 858 that is connected to theelectric circuit unit 856. The battery interface 654 is substantiallythe same as the battery interface 54 shown in FIG. 6, and removablyreceives the battery pack 100 that is used in the electric power tool200. The battery interface 854, the electric circuit unit 856, and theelectric motor 858 are housed in the vehicle body 814. An openable cover852 for attaching and removing the battery pack 100 is provided on thevehicle body 814.

The electric motor 858 is connected to both the wheels 836 and thecultivating rotor 822 via transmission belts 832 a, 832 b. Electricpower is supplied from the battery pack 100 attached to the batteryinterface 858 to the electric motor 856 via the electric circuit unit854. In this configuration, the electric motor 858 applies torque to thecutter 822 and the wheels 836, and both rotates the cultivating rotor822 and assists the user to push the electric power cultivator 800.Here, the aforementioned grip sensors are connected to the electriccircuit unit 856, and the electric circuit unit 856 will supply electricpower to the electric motor 858 only while the user is grasping thegrips 816. Thus, movement of the electric power cultivator 800 that isnot intended by the user will be prohibited. Here, the electric circuitunit 856 preferably adjusts the electric power supplied to the electricmotor 858 in response to the force applied by the user on the grips 816.

The electric power cultivator 800 does not need a dedicated batterypack, and can use the battery packs 100 used with the electric powertool 200 as a power source. Because of that, the user can effectivelyuse the electric battery packs 100 in his or her possession in both theelectric power tool 200 and the electric power cultivator 800. Becausethe battery packs 100 designed for use in the electric power tool 200have a high output, they can sufficiently function as a power source forthe electric power cultivator 800.

As described in the embodiments above, the battery pack 100 for use inthe electric power tool 200 can be effectively used as a power sourcefor driving the wheels on various electric wheeled apparatuses. In otherwords, as shown in FIG. 27, the battery pack 100 designed for variouselectric power tools 200 is not only a power source for driving the toolof these electric power tools 200, but also sufficiently functions as apower source for driving the wheels on the various electric wheeledapparatuses 10, 400, 500, 600, 700, 800.

In addition, the battery packs for use in electric power tools have ahigh output voltage and a large charge capacity, and also have superiorshock resistance and dust resistance. In addition, the battery packs canbe equipped with a sensor that detects the temperature of the secondarybattery cells, a sensor that detects the voltages of the secondarybattery cells, a controller, and memory, and can deliver and receivethis information to and from the equipment in which it is attached.Because battery packs for use in electric power tools are equipped witha large number of useful characteristics, the battery packs are notlimited to electric wheeled apparatuses, and can be effectively utilizedin other types of devices and equipment. Specifically, the battery packscan be effectively used in electric power cultivators (also referred toas management devices), air compressors, water pumps, portable lighting,back-up power supply for computers, and energy storage units for solarbattery systems and cogeneration systems, etc.

What is claimed is:
 1. An electric wheeled apparatus comprising: a mainbody; at least one wheel supported by the main body in a rotatablemanner; an electric motor configured to apply torque to the at least onewheel; a battery interface configured to removably receive at leastfirst battery pack and a second battery pack which are each originallydesigned as a power source of an electric power tool, wherein thebattery interface is configured to receive the first and second batterypacks while the first and second battery packs are detached from thepower tool; and an electric circuit unit configured to electricallyconnect the first and second battery packs attached to the batteryinterface with the electric motor, wherein the battery interfacecomprises a first positive connection terminal, a first negativeconnection terminal, a second positive connection terminal and a secondnegative connection terminal, the first positive connection terminal andthe first negative connection terminal are configured to be electricallyconnected with a positive terminal and a negative terminal of the firstbattery pack respectively when the first battery pack is attached to thebattery interface, the second positive connection terminal and thesecond negative connection terminal and configured to be electricallyconnected with a positive terminal and a negative terminal of the secondbattery pack respectively when the second battery pack is attached tothe battery interface, and the electric unit is configured toselectively be switched to form a series connection circuit in which thefirst positive connection terminal is electrically connected with thesecond negative connection terminal with the electric motor beingelectrically interposed in the connection circuit between the firstpositive connection terminal and the second negative connectionterminal, and in which the first negative connection terminal iselectrically connected with the second positive connection terminalwithout the electric motor being electrically interposed in theconnection circuit between the first negative connection terminal andthe second positive connection terminal, and the electric circuit unitis further configured to selectively be switched to form any one of theseries connection circuit and a parallel connection circuit in which thefirst positive connection terminal is electrically connected with thesecond positive connection terminal without the electric motor beingelectrically interposed in the connection circuit between the firstpositive connection terminal and the second positive connectionterminal, and in which the first negative connection terminal iselectrically connected with the second negative connection terminalwithout the electric motor being electrically interposed in theconnection circuit between the first negative connection terminal andthe second negative connection terminal.
 2. The electric wheeledapparatus as in claim 1, wherein the electric wheeled apparatus is anelectric bicycle, which further comprises: pedals configured to bepedaled by a user on the electric bicycle; and a user force transmissionconfigured to mechanically connect the pedals with the at least onewheel so as to transmit force applied to the pedals by the user to theat least one wheel.
 3. The electric wheeled apparatus as in claim 2,wherein the electric circuit unit is configured to control electricpower supply from the first and second battery packs to the electricmotor in accordance with the force applied to the pedals by the user. 4.The electric wheeled apparatus as in claim 1, wherein the electricwheeled apparatus is a carrier cart, the main body has a platformconfigured to support baggage, the at least one wheel includes a pair ofwheels; and the battery interface is arranged such that the first andsecond battery packs are partly located between the pair of wheels whenthe first and second battery packs are attached to the batteryinterface.
 5. The electric wheeled apparatus as in claim 4, wherein theelectric circuit unit is configured to control electric power supply tothe electric motor in accordance with a force applied to the carriercart by a user.
 6. The electric wheeled apparatus as in claim 1, whereinthe electric apparatus is a wheelbarrow, the at least one wheel is asingle wheel and the electric motor is an in-wheel incorporated in thesingle wheel.
 7. The electric wheeled apparatus as in claim 6, whereinthe electric circuit unit is configured to control electric power supplyto the electric motor in accordance with a force applied to thewheelbarrow by a user.
 8. The electric wheeled apparatus as in claim 1,wherein the electric wheeled apparatus is a suitcase, the main body isan openable case that supports the at least one wheel driven by theelectric motor, and the battery interface is arranged within theopenable case such that the first and second battery packs are able tobe attached to and detached from the battery interface from inside theopenable case.
 9. The electric wheeled apparatus as in claim 8, whereinthe electric circuit unit is configured to control electric power supplyto the electric motor in accordance with a force applied to the suitcaseby a user.
 10. The electric wheeled apparatus as in claim 1, wherein theelectric wheeled apparatus is an electric power mower having a cutter,and the electric motor is configured to apply torque to both of the atleast one wheel and the cutter.
 11. The electric wheeled apparatus as inclaim 10, wherein the electric circuit unit is configured to controlelectric power supply to the electric motor in accordance with a forceapplied to the electric power mower by a user.
 12. The electric wheeledapparatus as in any claim 1, wherein the electric wheeled apparatus isan electric power cultivator having a cultivating rotor, and theelectric motor is configured to apply torque to both of the at least onewheel and the cultivating rotor.
 13. The electric wheeled apparatus asin claim 12, wherein the electric circuit unit is configured to controlelectric power supply to the electric motor in accordance with a forceapplied to the electric power cultivator by a user.
 14. A combinationcomprising: an electric power tool; at least a first battery pack and asecond battery pack each configured to be detachably attached to theelectric power tool; a charger configured to electrically connect to andrecharge the first and second battery packs; and the electric wheeledapparatus as in claim 1, the battery interface of which is configured toremovably receive the first and second battery packs while the first andsecond battery packs are detached from the electric power tool.
 15. Theelectric wheeled apparatus as in claim 1, wherein the electric circuitunit comprises a first selection switch configured to selectivelyelectrically connect the first negative connection terminal with any oneof the second positive connection terminal and the second negativeconnection terminal, without the electric motor being electricallyinterposed in the connection circuit between the first negativeconnection terminal and the any one of the second positive connectionterminal and the second negative connection terminal.
 16. The electricwheeled apparatus as in claim 1, wherein the battery interface isconfigured to removably receive a third battery pack which is originallydesigned as a power source of the electric power tool, wherein thebattery interface is configured to receive the third battery pack whilethe third battery pack is detached from the power tool, the batteryinterface further comprises a third positive connection terminal and athird negative connection terminal which are configured to beelectrically connected with a positive terminal and a negative terminalof the third battery pack respectively when the third battery pack isattached to the battery interface, and when the electric circuit unitforms the series connection circuit, the third positive connectionterminal is electrically connected with the second negative connectionterminal without the electric motor being electrically interposed in theconnection circuit between the third positive connection terminal andthe second negative connection terminal, and the third negativeconnection terminal is electrically connected with the first positiveconnection terminal with the electric motor being electricallyinterposed in the connection circuit between the third negativeconnection terminal and the first positive connection terminal.
 17. Theelectric wheeled apparatus as in claim 16, wherein the electric circuitunit is further configured to selectively be switched to form any one ofthe series connection circuit and the parallel connection circuit inwhich the first positive connection terminal is electrically connectedwith both the second and third positive connection terminals without theelectric motor being electrically interposed in the connection circuitbetween the first positive connection terminal and either of the secondand third positive connection terminals, and the first negativeconnection terminal is electrically connected with both the second andthird negative connection terminals without the electric motor beingelectrically interposed in the connection circuit between the firstnegative connection terminal and either of the second and third positivenegative connection terminals.
 18. The electric wheeled apparatus as inclaim 1, wherein the electric circuit unit comprises a first selectionswitch and a second selection switch, the first selection switch isconfigured to selectively electrically connect the first negativeconnection terminal, with any one of the second positive connectionterminal and the third negative connection terminal, without theelectric motor being electrically interposed in the connection circuitbetween the first negative connection terminal and the any one of thesecond positive connection terminal and the third negative connectionterminal, and the second selection switch is configured to selectivelyelectrically connect the second negative connection terminal, with anyone of the third positive connection terminal and the third negativeconnection terminal, without the electric motor being electricallyinterposed in the connection circuit between the second negativeconnection terminal and the any one of the third positive connectionterminal and the third negative connection terminal.